The number of obese is increasing rapidly. Bariatric surgery is used to a greater and greater extent as treatment of obesity to obtain a greater and more permanent weight loss. The currently most commonly used surgical method is the gastric bypass (RYGB), which so far has proved to be the most effective way to achieve a greater and more permanent weight loss, reduction and maybe even elimination of many of the obesity-related health complication (diabetes, sleep apnea, pain due to osteoarthrosis etc.).